Pediatric angioedema without urticaria: A rare presentation of autoimmune thyroid disease with complete remission on levothyroxine therapy.

Angioedema without urticaria (AEwU) is an uncommon manifestation of autoimmune thyroid disease (AITD), rarely reported in the pediatric population. A 12-year-old boy presented with recurrent episodes of angioedema affecting the lips and eyelids for 6 months, unresponsive to antihistamines. There were no systemic symptoms, wheals, or identifiable allergic triggers. Laboratory evaluation revealed normal C1-inhibitor levels and function, ruling out hereditary angioedema. Notable findings included eosinophilia (14.4%) and elevated serum Immunoglobulin E levels (1617 IU/mL), while bone marrow flow cytometry and serum tryptase levels were normal. Autoimmune screening identified AITD with overt hypothyroidism (thyroid-stimulating hormone: 34 μIU/mL). A diagnosis of AEwU secondary to AITD was considered. Initiation of levothyroxine (62.5 μg/day) led to symptom resolution within 3-4 days, with no recurrence in eight months. AEwU secondary to AITD is a diagnosis of exclusion and should be considered in patients with unexplained angioedema after ruling out hereditary and allergic causes.